EUVD-2026-12417
GHSA-44mv-jq72-gj49
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Lifecycle Timeline
4DescriptionCVE.org
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to bound memory allocation when processing PSD image files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted PSD file. Mattermost Advisory ID: MMSA-2026-00572
AnalysisAI
Mattermost fails to properly bound memory allocation when processing PSD (Photoshop) image files, allowing authenticated attackers to exhaust server memory and trigger denial of service by uploading a specially crafted PSD file. The vulnerability affects Mattermost versions 11.3.0 and earlier, 11.2.2 and earlier, and 10.11.10 and earlier. With a CVSS score of 4.3 and a low attack complexity requirement, this represents a moderate but exploitable risk for organizations running affected versions where user file upload is permitted.
Technical ContextAI
The vulnerability exists in Mattermost's image processing pipeline, specifically in the handling of Photoshop (PSD) files during file upload and validation. The root cause is classified under CWE-789 (Memory Allocation with Excessive Size Value), which occurs when the application fails to validate or limit the size of memory allocations before processing untrusted input. The PSD file format is complex and supports multiple layers, channels, and metadata; attackers can craft malicious PSD files with exaggerated dimension or layer count values that cause the image processing library to allocate excessive memory without proper bounds checking. This affects Mattermost's file upload and image processing components across versions 11.3.x, 11.2.x, and 10.11.x product lines. The affected CPE identifiers are cpe:2.3:a:mattermost:mattermost_server:*:* across the vulnerable version ranges.
RemediationAI
Upgrade Mattermost Server to version 11.3.1 or later for the 11.3.x branch, version 11.2.3 or later for the 11.2.x branch, or version 10.11.11 or later for the 10.11.x branch. Refer to the official Mattermost security advisory (MMSA-2026-00572) at https://mattermost.com/security-updates/ for detailed patching instructions and compatibility notes. As a temporary mitigation prior to patching, disable file uploads via Mattermost's configuration settings or restrict the feature to trusted users only. Additionally, implement OS-level memory limits and resource quotas on the Mattermost process using container memory limits (if deployed in Docker/Kubernetes) or cgroups to prevent a single malicious upload from exhausting all available memory and impacting other services. Monitor Mattermost logs for repeated image processing errors or unusual memory consumption patterns that may indicate exploitation attempts.
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View allVendor StatusVendor
SUSE
Severity: Medium| Product | Status |
|---|---|
| openSUSE Leap 15.6 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | Fixed |
| openSUSE Leap 15.5 | Fixed |
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External POC / Exploit Code
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